ES2978091T3 - Multicomponent polymeric resin, methods for applying the same and composite laminated structure including the same base - Google Patents

Abstract

The achievements disclosed in this document relate to polymer resins having a thermoset primer and one or more additional components (for example, a second thermoset primer and/or a thermoplastic), composite laminates including them, methods for manufacturing and using them, and structures of composite laminates including them. (Automatic translation using Google Translate, not legally binding)

Description

DESCRIPTION

Multicomponent polymeric resin, methods for applying the same and composite laminated structure including the same base

High-volume production of structural parts focuses on low-cost materials and low assembly costs, but may initially require a long-term, high-capital investment in tooling and equipment. However, high production volume may not easily accommodate design variations.

Currently, low-volume production of parts involves low capital expenditure, expensive materials and high assembly costs, for example aluminium components. In general, low-volume production is still very expensive.

It is desirable to produce lightweight, strong and rigid composites for manufacturing a structural component, such as a chassis, panels for communication equipment, frames or body parts for transportation or vehicles (e.g., bicycles, motorcycles, trucks, etc.), agricultural applications (e.g., farming equipment), energy-related applications (e.g., wind, solar energy), satellite applications, aerospace applications, construction materials (e.g., building materials and the like), and consumer products (e.g., furniture, toilet seats, and electronics, among others).

It is desirable to produce lightweight, strong composite components with good energy absorption for manufacturing a chassis or body component, such as an automobile hood or other body panel. Body components may be designed to provide energy absorption during an automobile accident. For safety reasons, the automobile hood or body components may be designed to have some damping or energy absorption characteristics.

Composite components for transportation (e.g., car, truck, or any vehicle), agricultural equipment, construction equipment, or aerospace industries can significantly improve fuel efficiency and reduce carbon emissions. The composite may include carbon fibers or glass fibers. Carbon fibers can be stiffer, stronger, and less heavy than glass fibers, but they can generally be more expensive. Carbon fiber-reinforced components can be about 20% lighter than aluminum components and about 50% lighter than some steel components. Carbon fiber-reinforced composites can have a higher strength-to-weight or stiffness-to-weight ratio than aluminum and steel.

Currently, composite components are typically manufactured using conventional processes, including high-pressure resin transfer molding (RTM). Composite components may also be comprised of preimpregnated fibers (“prepreg”) and may require an oven or autoclave to cure the prepreg. Traditionally, carbon fiber-reinforced composite components are not cost-competitive compared to metal components for several reasons. First, high-pressure RTM may require relatively expensive equipment and high pressure to flow a polymeric resin to impregnate the fibers and reduce surface defects (e.g., pinholes or unwanted porosity). Despite the high-pressure application of the resin, the surface may still have pinholes or surface defects. A surface with such defects may not exhibit the desired surface finish or be cosmetically undesirable. Such surface defects may also make painting the composite surface difficult. Second, high-pressure RTM can also require longer cycle times to manufacture a composite component compared to metal components. For example, production cycle times for carbon fiber parts – including heating, curing, and cooling the composite component – can take about 45 minutes or more compared to seconds for steel or aluminum parts. Third, material cost can be high for virgin carbon fibers, and fiber waste from RTM can also be very high. For example, when manufacturing a composite component with complicated shape or geometry, up to 40% of the original carbon fibers can be wasted. In addition, the production yield of RTM parts is relatively low compared to that of metal parts due to surface defects.

Manufacturers continue to look for low-cost alternative materials, low-cost tooling, and faster cycle times to reduce the cost of producing composite components.

EP0478033 discloses a process for manufacturing an aminoplast impregnated sandwich panel consisting of a honeycomb and a skin by means of an autoclave, characterized in that at least one of the honeycomb and the skin is impregnated with aminoplast and the sandwich panel is placed in an autoclave under a sheet of flexible material, which flexible material is at least partially gas-tight and sealed at its edges, on which flexible material a first pressure is applied and under which flexible material a second pressure is applied, which is lower than the first pressure whereby the second pressure is at least as high as the vapour pressure of water at the curing temperature of the aminoplast. Honeycomb sandwich panels manufactured by applying a process according to the invention are particularly suitable for use in applications with high demands imposed with respect to strength and stiffness in combination with high demands with respect to fire resistance. Examples are aircraft, housing construction, trains, motor vehicles and ships.

Summary

The embodiments described herein relate to methods for applying the polymeric resin to form fiber-reinforced composite sandwich structures and fiber-reinforced composite structures.

In one embodiment, a method for forming a composite laminate structure is disclosed according to claim 1. In one embodiment, a composite laminate structure is disclosed according to claim 16.

Brief description of the drawings

The drawings illustrate various embodiments, where identical reference numbers refer to identical or similar elements or features in different views or embodiments shown in the drawings.

FIG. 1A is a diagram of a pressure vessel for heating and spraying a polymeric resin according to an embodiment not covered by the subject matter of the claims.

FIG. 1B is the diagram of the container of FIG. 1A before mixing the polymer resin and hardener.

FIG. 2 is an isometric view of the pressure vessel of FIG. 1A, according to an embodiment not covered by the subject matter of the claims.

FIG. 3 is an isometric view of a container of FIG. 1A containing a polymeric resin including a hardener, according to an embodiment not covered by the subject matter of the claims.

FIG. 4 is a flow chart of a method for spraying a polymeric resin according to an embodiment not covered by the subject matter of the claims.

FIG. 5 is a schematic of a device for forming sheets of recycled fibers according to an embodiment not covered by the subject matter of the claims.

FIG. 6 is a photograph of the fiber sheets of FIG. 5 after needling in accordance with embodiments not covered by the subject matter of the claims.

FIG. 7 is a photograph of the fiber sheets of FIG. 5 with a mesh between two fiber sheets according to embodiments not covered by the subject matter of the claims.

FIG. 8 is a photograph of a composite sandwich including a core made of drinking straws in accordance with embodiments of the present disclosure.

FIG. 9 is a cross-sectional view of a composite sandwich according to one embodiment.

FIG. 10 is a cross-sectional view of a composite sandwich according to one embodiment.

FIG. 11 is a cross-sectional view of a component formed by a composite sandwich, a metal insert and reinforced with an NCF according to one embodiment.

FIG. 12 is a flow chart for a method of forming a composite sandwich according to one embodiment.

FIG. 13 is a flow chart for a method of forming a composite sandwich according to one embodiment.

Detailed description

The embodiments described herein relate to polymeric resins having a first thermoset and one or more additional components (e.g., a second thermoset and/or a thermoplastic), composite laminates including the same, methods of making and using the same, and embodiments according to the invention of composite laminate structures including the same. The embodiments described herein provide a polymeric resin that includes a liquid mixture or blend of a first thermoset (e.g., a polyurethane) and at least one second thermoset (e.g., an epoxy) and/or another polymeric material such as one or more thermoplastics. Polymeric resins are typically in liquid form prior to curing and become solid after curing, which is a crosslinking process. The polymeric resin may include one or more hardeners to catalyze the curing of one or more components of the resin. Polymeric resins may be used as adhesives. Two or more thermosets may be used to form a composite laminate structure, such as a carbon fiber composite laminate. Composite laminates may include one or more layers of polymeric resin on, or at least partially incorporated into, a fiber sheet or mat.

The polymer resin has a low viscosity at high temperatures, so the polymer resin can be sprayed at a low pressure, such as less than 620528 Pa (6.2 bar, 90 psi).

Polymeric resin can also form microfoams during curing. Microfoams can adhere to relatively stiffer materials (e.g. plastics) well, especially when the materials have a small bonding surface, for example open ends of cells such as tubes (e.g. plastic pipes) as discussed in more detail below.

As discussed in greater detail below, the polymeric resin can be used to form composite sandwiches that include a "hard" core or a "soft" core. The "hard" core can effectively transfer load from one end of the core to the other end of the core. For example, the "hard" core can be formed from a blank core that includes one or more plastic materials and can include a plurality of cells having open ends (e.g., closely packed substantially parallel plastic tubes). The plurality of cells can be at least partially defined by one or more corresponding cell walls (e.g., the plastic material can define a honeycomb-like structure, where the cells can have any number of suitable shapes). In some embodiments, the compressible cells of the blank core can be formed or defined by tubes or straws. In some embodiments, the cells may be tubes, such as drinking straws (e.g., each straw may define a corresponding cell of the core and adjacent cores may define additional cells in the gaps or spaces between them). Plastic straws, which are commercially manufactured from polycarbonate at very low cost, may be secured together in a generally parallel arrangement. The hard core may alternatively or additionally include a high-density foam. The hard core may provide high flexural rigidity for the composite sandwich. In the case of cells, more specifically plastic tubes, the core may have a plurality of cells or tubes, each having open ends. The "hard" core may increase the flexural rigidity of the composite sandwich more than the "soft" core.

Further details regarding suitable cores that may be used in any of the embodiments described herein can be found in PCT International Application No. ------entitled "Composite Sandwich With High Flexural Stiffness And Light Weight" and filed concurrently herewith (claiming priority to U.S. Provisional Patent Application No. 62/007,614 (Attorney Docket No. P243720.U.S.01), entitled "Composite Sandwich With High Flexural Stiffness And Light Weight," filed June 4, 2014). The core of the composite sandwich may include a bundle of plastic tubes, such as drinking straws, and may be suitable for manufacturing automotive components, such as a chassis.

The "hard" core, such as that formed by open-ended plastic cells such as drinking straws or tubes, can be difficult to bond to the composite laminate (e.g., one or more layers of composite laminate forming a single layer over the core) using a conventional epoxy. For example, the composite laminate is more likely to peel off the "hard" core when a conventional epoxy is used. The polymeric resins according to the embodiments described herein solve the peeling problem of the composite sandwich that includes a "hard" core by providing sufficient adhesion thereto (e.g., by increased adhesion with microfoams formed by the polymer/epoxy mixture that can extend at least partially into the cells through the open ends).

In contrast, a "soft" core may not transfer load from one end of the core to the opposite end of the core when a load is applied to one end of the core; for example, the "soft" core may be formed from paperboard, or cardboard, or low-density foams, and the like. The "soft" core may absorb more energy or impact vertically than the "hard" core (e.g., in a direction substantially perpendicular to the composite laminates) assuming the impact is along a Z-axis (e.g., generally perpendicular to the face of the laminated composite). The "hard" core can absorb more energy horizontally, such as along the plane of the composite laminates (e.g., in an XY plane) that is perpendicular to the Z axis. The composite sandwich, including paperboards, can be used for automotive hoods, surface panels (e.g., Class A surface panels having minimal pores or porosity), aerospace applications or consumer products (e.g., furniture), or building materials or similar applications where energy absorption is desired. The manufacturing process may be different for the "soft" core composite sandwich from the "hard" core composite sandwich, because the "soft" core does not transfer a load having a vector substantially perpendicular to the core as well as the "hard" core. Details regarding apparatus and methods for manufacturing composite sandwiches with a "soft" core are described in PCT International Application No. -------(Attorney Docket No. 44353WO01_496714-23), entitled "Composite Structure Exhibiting Energy Absorption and/or Including a Defect-Free Surface," which is filed concurrently herewith.

Resin composition

According to one or more embodiments beyond the scope of the appended claims, the polymeric resin may include a mixture of one or more thermosets having a relatively low viscosity and one or more thermosets and/or one or more thermoplastics having a relatively high viscosity, according to the invention, the mixture includes a polyurethane with an epoxy. The mixture may have a relatively low viscosity (e.g., about 40 mPa s or less) at room temperature. In some embodiments, explained in more detail below, the polymeric resin may include one or more of at least one hardener, at least one Group VIII metallic material, at least one filler material or at least one thermoplastic. The low viscosity of the polymeric resin may be mainly due to the low viscosity thermoset (e.g., a polyurethane, such as VITROX provided by Huntsman Polyurtanes which has a viscosity of about 0.15 Pa s (150 centipoise) at room temperature), because the other high viscosity thermoset (e.g., EP05475 epoxy provided by Momentive) generally has a relatively higher viscosity than the low viscosity thermoset. The viscosity of the polyurethane may be about 30-40 mPa-s, and the viscosity of the epoxy may be about 50-70 mPa-s (or in a special case about 15 mPa-s (for VoraForce 5300 from Dow)). The polymeric resins described herein may have relatively short cure times while exhibiting relatively small shrinkage (e.g., below about 3%). EP05475 epoxy has a cure time of 5 minutes at 120°C and a Tg of about 120°C, while the polyurethane cure time may be about 1 hour or more and a Tg less than about 250°C. As used herein, the term "cure" or "cured" includes the meanings of curing or at least partially or fully cured.

A polyurethane thermoset may provide one or more of a desired flexural strength, resilience, low viscosity, or foaming capability (e.g., ability to form microfoams during formation of composite laminate structures) to the polymer resin. An epoxy thermoset may provide a desired energy absorption or mechanical failure profile to the polymer resin, such as brittle fracture along a force vector parallel to the part surface. The epoxy thermoset may provide a water-resistant (e.g., airtight) character to the resulting composite laminate or improved load transfer capability (e.g., a harder surface).

In some embodiments, the polymeric resin can include at least one curing agent or hardener, the hardener can be configured to cause one or more components of the polymeric resin to cure. For example, when the polymeric resin includes epoxy and polyurethane, the polymeric resin can include a hardener for one or both of the epoxy or the polyurethane. Suitable hardeners for epoxies and polyurethanes can include any of those known to cure the epoxies and polyurethanes described herein. For example, at least one hardener can include amine-based hardeners for epoxies and polyisocyanate-containing hardeners for polyurethanes. The curing agent or hardener can be present in the polymeric resin in a ratio of about 1:100 to about 1:3 parts of curing agent or hardener per part of polymeric resin or component thereof. In some embodiments, the hardener may be composed to begin curing at about 50°C or higher, such as about 50°C to about 150°C, about 70°C to about 120°C, or about 70°C to about 90°C, or about 70°C or higher.

In some embodiments, the polymeric resin may also include a blend of one or more thermosets and a thermoplastic, such as a blend of epoxy and thermoplastic fibers, or a blend of polyurethane and thermoplastic fibers, or a combination of the foregoing. The thermoplastic may be included to provide toughness or resilience to the cured composite part. Suitable thermoplastics may include one or more of a polypropylene, a polycarbonate, polyethylene, polyphenylene sulfide, polyetheretherketone (PEEK) or other polyaryletherketone, or an acrylic. The thermoplastic may represent about 1% to about 20% of the polymeric resin by volume. The polymeric resin may also include a thermoset with a low viscosity, such as polyurethane. The polymeric resin may also include a thermoset with a relatively high viscosity, such as epoxy, which may be heated to reduce the viscosity for spraying using a pressure vessel or commercial spray heads.

The polymeric resin may have better load transfer capability and improved mechanical performance, including higher stiffness, strength, modulus, and toughness, among others, than resins containing only polyurethane or only epoxy. The polymeric resin may also have a low volume shrinkage from the uncured liquid state to the cured solid state equal to or less than 3% during curing, such as about 1.5% to about 3%, about 2% to about 3%, about 2.5% to about 3%, or about 2.5%. The low shrinkage allows for better dimensional control of the finished composite components.

Epoxy generally has a shorter pot life than polyurethane. In some embodiments, the epoxy may be mixed a few hours before use. In contrast, polyurethane generally has a longer pot life than epoxy, is based on isocyanate chemistry, and may have adjustable pot life and rapid cure capabilities. In some embodiments, the polyurethane or epoxy may include one or more fire retardant components. For example, the polymeric resin may include a phenolic epoxy or equivalents thereof.

Polymer resin, such as a mixture of polyurethane and epoxy, may be water-resistant after curing due to the properties of one or more of the materials it contains. Generally, a thermoset (e.g., polyurethane microfoams) may have water permeability, while other thermosets (e.g., epoxy) may be water-resistant. Therefore, the mixture may be water-resistant or water-sealed when the water-resistant thermoset is used in sufficient amount. For example, when the amount of epoxy in a polyurethane resin/epoxy polymer is more than about 28% by volume (e.g., 30% by volume), the mixture may exhibit a substantially water-resistant character.

In addition, the polymeric resin may allow for the formation of polyurethane foams, which may improve the bonding of the composite laminates to the core of the composite sandwich. It was found that the composite laminates formed in accordance with the present disclosure do not peel away from the "hard" core, such as plastic tubes. In some embodiments herein, a selected amount of foaming may be desired in the polymeric resin, such as by one or more components therein (e.g., the polyurethane reacts to form a microfoam). As the polyurethane in the polymeric resin foams, the foam (e.g., microfoam) infiltrates according to the invention into the cells or tubes of the core thereby forming a mechanical bond with the core. Such infiltration may take place at the open ends of the core and may include at least partial infiltration from the open ends inward.

In some embodiments, the polymeric resin may include a liquid blend or mixture of epoxy and polyurethane. In one possible embodiment beyond the scope of the present claims, the polymeric resin may include at most about 50% by volume of epoxy including a curing agent or hardener, up to about 20% by volume of a Group VIII metallic material, and the remaining volume may be polyurethane. When mixed, the epoxy may react (e.g., thermally and/or chemically) with the polyurethane. When the amount of epoxy exceeds a certain amount (e.g., about 40% by volume), an undesirable reaction may occur, which may cause unwanted heat and/or uncontrolled foaming. In some embodiments beyond the scope of the appended claims, the polymeric resin may include less than about 50% by volume of epoxy. In some embodiments, the polymeric resin includes less than about 30% by volume of epoxy. In some embodiments, the polymeric resin includes less than about 20% by volume of epoxy. In some embodiments, the polymeric resin includes less than about 10% by volume of epoxy. In some embodiments, the ratio of polyurethane to epoxy in the polymeric resin may be about 1:1 or more, such as about 2:1, about 2.5:1, about 3:1, about 3.5:1, about 4:1, about 5:1, about 7:1, or about 9:1.

In one embodiment, the polymeric resin may include polyurethane, epoxy, and at least one hardener. The at least one hardener may be composed to cause one or more components of the polymeric resin to begin to cure. The at least one hardener may be specifically composed to cause only one component of the polymeric resin to cure. Suitable hardeners may include amine-based hardeners for epoxies, polyisocyanate-containing hardeners for polyurethanes, or any other hardener suitable for causing cure of one or more components of the polymeric resins described herein. In one embodiment, the epoxy can be about 10% to about 35% of the polymeric resin by volume, the at least one hardener can be present in a ratio of about 1:100 to about 1:3 of the polymeric resin or component thereof (e.g., a 1:5 ratio of hardener to epoxy or hardener to resin) by volume, and the polyurethane can constitute at least a portion of the remainder of the polymeric resin. In one embodiment, the epoxy can be about 25% to about 35% of the polymeric resin by volume, the at least one hardener can be present in a ratio of about 1:10 to about 1:3 or about 1:5 to about 1:3 of the polymeric resin or component thereof (e.g., epoxy or polyurethane) by volume, and the polyurethane can constitute at least a portion of the remainder of the polymeric resin. The at least one hardener may be composed or used in an amount sufficient to cause the polymeric resin to cure (e.g., at least partially harden) in a desired time, such as about 3 hours or less, about 2 hours or less, about 1 hour or less, about 30 minutes or less, about 20 minutes or less, about 15 minutes or less, or about 10 minutes or less, depending on the time required to apply the polymeric resin.

The percentage or proportion by volume of epoxy sufficient to cause an undesired or uncontrolled reaction (e.g., uncontrolled foaming) between the epoxy and the polyurethane can be varied by the addition of a Group VIII metallic material. The Group VIII metallic materials can serve to stabilize or mediate the reaction of the epoxy and polyurethane in the polymeric resin. The Group VIII metallic material can include cobalt (Co), nickel (Ni), iron (Fe), ceramics (e.g., ferrites) including one or more thereof, or alloys including any of the same, among others. The Group VIII metallic material can be equal to or less than 20% by volume of the polymeric resin, such as about 0.1% to about 20%, about 0.5% to about 10%, about 1% to about 5%, about 2%, about 3%, or about 4% or less of the volume of the polymeric resin. In some embodiments, the Group VIII metallic material may be less than about 15% by volume of the polymeric resin, less than about 10% by volume, less than about 5% by volume, or less than about 1% by volume of the polymeric resin. By adding the Group VIII metallic material to the polymeric resin, the amount of epoxy therein may be increased to provide the desired surface hardness and/or create a substantially impermeable surface. For example, as the volume percentage of epoxy in the polymeric resin increases above about 25%, the cured composite may begin to exhibit impermeable properties. If impermeable properties are desired in the final product, the polymeric resin may include about 28% epoxy by volume or more, such as about 30% or more, about 30% to about 50%, about 32% to about 40%, or about 35% epoxy by volume. To substantially reduce or eliminate pores or micropores in the resulting composite material as the amount of epoxy in the polymer resin is increased, Group VIII metallic material can be added to reduce or control foaming. Although Group VIII metallic material can help stabilize the polymer resin, Group VIII metallic material may increase the cost of the polymer resin and the composite component or increase the viscosity of the polymer resin.

In some embodiments, one or more fillers may be added to the polymeric resin mixture to reduce shrinkage during cure. For example, if a very fast curing epoxy is selected, such as Dow Voraforce 5300, the fast curing epoxy may exhibit higher shrinkage than slower curing epoxies, such as about 7% by volume for Voraforce 5300. In some embodiments, the use of one or more fillers in the polymeric resin may reduce such shrinkage in the same resin. Such fillers may include one or more of calcium carbonate, aluminum trihydroxide, alumina powders, silica powders, silicates, metal powders, or any relatively inert or insoluble (in the polymeric resin) salt. Excessive filler material may cause the cured composite to exhibit undesirable brittleness. In some embodiments, the filler may be about 30% of the volume of the polymeric resin or less, such as about 1% to about 30%, about 2% to about 20%, about 5% to about 15%, about 10% to about 30%, about 1% to about 10%, more than zero percent to about 10%, about 1% to about 7%, about 3% to about 9%, less than about 10%, or about 25% of the volume of the polymeric resin. In some embodiments, the filler may be about 10% of the volume of the polymeric resin or more, such as about 50% or about 75%. As the resin cures, the filler material does not shrink like the polymeric resin. Thus, the volume of polymeric resin displaced by the filler material provides a stable volume in the resulting composite material, thereby reducing the overall impact of shrinkage of the composite material. Such fillers may allow for faster cure times while also reducing shrinkage that typically occurs during rapid cures. For example, the cure time of a polymeric resin described herein may be reduced to about 6 minutes or less, such as about 3 minutes or less, about 90 seconds or less, about 60 seconds, or about 40 seconds, while maintaining a shrinkage of less than 3% by volume. Although the filler may help reduce or eliminate shrinkage, the filler may increase the cost of the polymeric resin and the composite component or increase the viscosity of the polymeric resin. In one embodiment, the combination of one or more of epoxy, polyurethane, thermoplastic, Group VIII metallic material or filler material can be configured to provide a net shrinkage of less than about 3% by volume and/or still exhibit a viscosity low enough to be sprayed from a spray tip at a relatively low pressure.

When the viscosity of a polymeric resin is relatively high (e.g., above 620528 Pa (6.2 bar, 90 psi)), it may be more difficult to spray the polymeric resin and it may take longer and/or higher line pressure to spray the polymeric resin. In an uncured state, the polymeric resins described herein may exhibit a relatively low viscosity (e.g., flow easily) at elevated temperatures and can be more easily spread manually or sprayed with a low-cost tool, such as a pressure vessel and sprayer, at a relatively low pressure (e.g., at about 620528 Pa (6.2 bar, 90 psi) or less) which can significantly reduce the high cost associated with a commercial liquid spray head while still providing a desired resilience and/or mechanical failure profile to the cured composite laminate enclosing it. A polymeric resin sprayer utilizing a pressure vessel may be suitable for prototyping or low volume production of relatively small parts.

In some embodiments, the polymeric resin may include an epoxy, a polyurethane, and one or more of at least one thermoset, at least one hardener, at least one Group VIII metallic material, or at least one filler. One or more of the above polymeric resin components may be used in combination with each other in any of the respective volume amounts described herein without limitation. For example, in one embodiment, the polymeric resin may include polyurethane, epoxy, and at least one thermoplastic such as PEEK. The epoxy may be about 10% to about 35% of the polymeric resin by volume, the thermoplastic may be about 1% to about 20% of the polymeric resin by volume, and the polyurethane may constitute the remainder of the polymeric resin. In one embodiment, the epoxy can be about 25% to about 35% of the polymeric resin by volume, the thermoplastic can be about 3% to about 15% of the polymeric resin by volume, and the polyurethane can constitute the remainder of the polymeric resin.

In one embodiment, the polymeric resin can include polyurethane, epoxy, and at least one Group VIII metallic material. The epoxy can be about 10% to about 35% of the polymeric resin by volume, the at least one Group VIII metallic material can be about 0.1% to about 20% of the polymeric resin by volume, and the polyurethane can constitute the remainder of the polymeric resin. In one embodiment, the epoxy can be about 25% to about 35% of the polymeric resin by volume, the at least one Group VIII metallic material can be about 5% or less of the polymeric resin by volume, and the polyurethane can constitute the remainder of the polymeric resin.

In one embodiment, the polymeric resin can include polyurethane, epoxy, and at least one filler. The epoxy can be about 10% to about 35% of the polymeric resin by volume, the at least one filler can be about 1% to about 30% of the polymeric resin by volume, and the polyurethane can constitute the remainder of the polymeric resin. In one embodiment, the epoxy can be about 25% to about 35% of the polymeric resin by volume, the at least one filler can be about 1% to about 10% or about 3% to about 20% of the polymeric resin by volume, and the polyurethane can constitute the remainder of the remaining polymer.

In one embodiment, the polymeric resin may include one or more of polyurethane, epoxy, at least one thermoplastic, at least one hardener, at least one Group VIII metallic material, and at least one filler. When present, the epoxy can be about 10% to about 40% (e.g., about 10% to about 35% or about 25% to about 35%) of the polymeric resin by volume, the thermoplastic can be about 1% to about 20% (e.g., about 3% to about 15%) of the polymeric resin by volume, the at least one hardener can be present in a ratio of about 1:100 to about 1:3 (e.g., about 1:10 to about 1:3 or about 1:5 to about 1:3) of the polymeric resin or component thereof by volume, the at least one Group VIII metallic material can be about 0.1% to about 20% (e.g., about 10% or less or about 5% or less) of the polymeric resin by volume, the at least one filler can be about 1% to about 30% of the polymeric resin or component thereof. (for example, about 1% to about 10% or about 3% to about 20%) of the polymeric resin by volume, and the polyurethane may constitute the remainder (for example, about 10% to about 90% or about 25% to about 75%) of the polymeric resin by volume.

Apparatus and methods for applying polymeric resin.

The polymeric resins described herein can be applied to a fiber sheet, core, or other component of a composite structure by one or more of the following methods: spraying or hand spreading (e.g., trowel, roller, brush, or spatula). The polymeric resin can be easily sprayed onto a fiber sheet using a pressure vessel or canister, at a much lower cost than conventional liquid spray heads. The pressure vessel is a low-cost alternative for prototyping and low volume production of small parts. FIG. 1A is a simplified diagram of a pressure vessel for spraying polymeric resin in accordance with embodiments of the present disclosure. A pressure vessel 100 (e.g., heated pressure vessel or other pressurized vessel capable of maintaining or increasing pressure and heating a fluid) includes a pressure vessel 118 with a cover 116, each configured to contain an increased pressure. Pressure vessel 118 holds a heated fluid (e.g., water) 102 therein for heating a liquid polymeric resin 104 in a container 110. Container 110 may include a rigid and/or resilient container, such as a plastic bag. Container 110 may be constructed of a substantially inert material (e.g., substantially inert to the components of the polymeric resin). A first tube 114 may be connected to container 110 to provide one or more components of resin 104 in a liquid form, and a second tube 112 may be connected to container 110 to provide one or more different components of resin 104 also in a liquid form.

FIG. 1B is a simplified diagram of the container of FIG. 1A prior to mixing a polymeric resin and a hardener in accordance with embodiments not covered by the claimed invention.

Within the vessel 110, a divider 108 may separate the polymeric resin 104A from a hardener 104B prior to spraying. A first tube 114 may be connected to the vessel 110 to provide the resin 104A in a liquid form, and a second tube 112 may be connected to the vessel 110 to provide the hardener 104B also in a liquid form. When the divider 108 is removed, the resin 104A and hardener 104B may be mixed. One of the first and second tubes 112 and 114 may be sealed or connected to a pressure source prior to placing the vessel 110 into the water 102 within the pressure vessel 118, while the other tube may be left open to act as an outlet for spraying the polymeric resin. In one embodiment, the warm fluid may be a heated liquid (e.g., water) or gas (e.g., steam).

FIG. 2 is an isometric view of the pressure vessel of FIG. 1A according to an embodiment not covered by the claimed invention.

The pressure vessel 200 includes an air connection 202 to an air outlet, which provides an air pressure of approximately 620528 Pa (6.2 bar, 90 psi).

The pressure vessel 200 may spray the polymeric resin from a connection 204 at a pressure generally less than 620528 Pa (6.2 bar, 90 psi), for example, 482633 Pa (4.8 bar, 70 psi). In some embodiments, the pressure vessel 200 may spray the polymeric resin at an air pressure of about 723950 Pa (7.2 bar, 105 psi). In some embodiments not covered by the claimed invention, one or more of the pressure vessel 200 or the plastic bag therein may include an agitator element therein. The agitator elements may include an ultrasonic processor (e.g., sonicator), stir bar, or other vibrating or agitating member. For example, the pressure vessel 200 may be configured as an ultrasonic bath having an adjustable temperature control.

FIG. 3 is an isometric view of a plastic bag containing a polymeric resin according to one embodiment. As shown, a plastic bag 302 (e.g., container) contains a premixed polymeric resin that includes a hardener. The plastic bag may be placed into pressure vessel 200 to heat the polymeric resin contained therein. The plastic bag 302 includes connection 204 for extruding the polymeric resin when the plastic bag is placed into pressure vessel 200. The plastic bag may be made of a plastic material selected to remain substantially inert to the polymeric resin or its components.

FIG. 4 is a flow chart of a method for spraying a polymeric resin according to embodiments not covered by the claimed invention.

Method 400 begins by mixing resin and hardener in a vessel to form a polymeric resin in action 402. Mixing may be accomplished by using hands or other tools to squeeze the bag at room temperature. Mixing may be aided by use of the agitator member. Mixing may include mixing one or more of a first thermoset (e.g., polyurethane), a second thermoset (e.g., epoxy), a Group VIII metallic material (e.g., ferrites), a thermoplastic, a filler, or the hardener.

The method 400 includes placing the vessel in a pressure vessel to heat the polymeric resin in action 406. The temperature of the fluid in the pressure vessel may be below the temperature at which the hardener begins to cure. For example, the water may be maintained at an application (e.g., spray) temperature below the curing temperature of the hardener, such as at about 50° C., while the hardener begins to cure at an elevated temperature, e.g., about 70° C., when the polymeric resin is a blend of polyurethane and epoxy. The hardener may be chosen to obtain the same or similar cure time for the epoxy and polyurethane at the same temperature. Equal or similar cure times may allow the two thermosets (e.g., epoxy and polyurethane) to complete cure together without lengthening the curing process due to one of the thermosets in the polymeric resin remaining uncured for a longer period.

In another embodiment, not covered by the claimed invention, when the polymeric resin includes an epoxy, the water can be maintained at a higher application temperature (e.g., spraying) to reduce viscosity, such as about 80°C-85°C or less, while the hardener for the epoxy can begin curing at about 90°C. By preheating the polymeric resin without beginning to cure, the viscosity of the polymeric resin can be reduced prior to application (e.g., to about 0.3 Pa s (300 centipoise) or less at about 70°C), making it easier to spray the polymeric resin at low pressure. In addition, the curing time of the polymeric resin can be shortened by preheating the resin in the pressure vessel or a commercial spray system, since it may take less time for the preheated polymeric resin to reach the gel point and therefore the polymeric resin can cure in a shorter time.

In one embodiment according to the invention, the polymeric resin includes a mixture of a polyurethane and an epoxy and the temperature is selected to maintain the desired viscosity of the polymeric resin without substantially curing the polymeric resin. In one embodiment according to the invention, the temperature can be selected to maintain the polymeric resin at a viscosity below about 0.3 Pa s (300 centipoise) without curing the polymeric resin. The temperature in the pressure vessel can be about 90 °C or less, and according to the invention is about 40 °C to about 85 °C, about 50 °C to about 70 °C, about 50 °C, about 80 °C, or about 65 °C or less to maintain the viscosity of the polymeric resin below about 0.3 Pa s (300 centipoise).

Method 400 also includes spraying the polymer resin at low pressure in action 410. The (low) pressure may be provided from an air outlet, which is typically 620528 Pa (6.2 bar, 90 psi). By using the air source from the air outlet, no additional compressor or the like is needed. The spray pressure may be lower than 620528 Pa (6.2 bar, 90 psi) for safety; for example, 482633 Pa (4.8 bar, 70 psi) may be used.

One of the benefits of using the polymeric resin to impregnate the fibers of a fiber sheet is to allow the use of low pressure to easily spray the polymeric resin through the pressure vessel or a commercial spray system. The polymeric resin may include a mixture of a thermoset with a high viscosity at room temperature (e.g., about 50-70 mPa s or more) and a thermoset with a low viscosity at room temperature (e.g., below about 40 mPa s), and may optionally also include one or more of a thermoplastic (e.g., blended fibers) to improve toughness, a Group VIII metallic material to stabilize the reaction of the polyurethane and epoxy, and/or a filler material to reduce shrinkage. The polymeric resin mixture may be composed such that the polymeric resin has a low viscosity, which may be further reduced by heating the polymeric resin in the pressure vessel prior to spraying as described above. Other commercial liquid spray heads may also be used to spray the polymeric resin. However, commercial liquid spray heads are much more expensive than pressure vessels. Therefore, the cost of tooling to spray the polymer resin is significantly reduced when the pressure vessel is used. Commercial liquid spray heads may be more suitable and used in high volume production of large parts and may be used with any of the embodiments described herein.

Carbon fibers and recycled fibers from RTM waste

Carbon fibers can be supplied in bundles, such as TORAY 1k, 3k, 6k, 12k, 24k and 48k. Carbon fibers may also include some binders on the outer surface of the fibers, so that the fibers can be bundled together when the carbon fibers are heated to a high temperature. Fiber waste from RTM can be very high, for example up to about 40%, depending on the shape or geometry of the product. Fiber waste can be generated by cutting off excess fiber from a virgin (e.g. unused) fiber sheet prior to the RTM operation. Fiber waste is usually in the form of unresined RTM sheet. Surplus or waste fibers can be recycled for further use. Recycled fiber sheets can be formed from waste fibers of any type, such as carbon fibers, glass fibers or plastic fibers. Specifically, the waste fiber sheet can first be cut into smaller squares, such as 35 by 35 mm2. The smaller squares of the waste fiber sheet can then be pulverized to break the bundles into filaments or individual fibers, which can be formed into recycled fiber sheets. Recycled fiber sheets are much cheaper than virgin fibers.

FIG. 5 illustrates a simplified device for forming recycled fiber sheets in accordance with embodiments of the present disclosure. The device 500 may include a moving belt 506, a hopper 502, and two rollers 508A-B. To make fiber sheets from recycled fibers, filaments may be deposited onto moving belt 506 through hopper 502, including an opening 504 at the bottom of hopper 502, which may be agitated to randomly arrange staple fibers 512 onto belt 506 through opening 504. Moving belt 506 may pass through two heated rolls 508A-B to form a fiber sheet 510, which includes randomly oriented staple fibers 512, and may be nearly isotropic in that the fibers are slightly oriented along the direction of movement of belt 506. Two rolls 508A-B may be heated to an elevated temperature, for example, about 80° C., so that the fibers are bonded together by binders on the outer surface of the fibers.

FIG. 6 is a photograph of the fiber sheets 510 of FIG. 5 after preparation in accordance with embodiments not covered by the claimed invention.

The fiber sheet 510 may be punched to form holes 602 to allow polymeric resin to flow through the fibers to form a composite laminate, as shown in FIG. 6. The polymeric resin embeds the randomly oriented discontinuous fibers.

Multiple fiber sheets may be used to form a composite laminate (e.g., one or more layers forming a single layer over the core) or skin. FIG. 7 is a photograph of the fiber sheets of FIG. 5 with a mesh between two fiber sheets in accordance with embodiments not covered by the claimed invention.

Multiple fiber sheets 700 include a plastic mesh 702 positioned between two fiber sheets 704A and 704B, as shown in FIG. 7. The mesh 702 may help retain staple fibers in the sheets. The mesh 702 may be formed of a plastic, including, but not limited to, nylon or polyamide.

Polymeric resin to form a composite sandwich

The polymeric resin may be used to form a composite structure, including a core sandwiched between at least two composite laminates ("composite sandwich"), such as one or more composite laminates on each side of the core. In some embodiments beyond the scope of the appended claims, the polymeric resin may include a liquid mixture of a first thermoset and a second thermoset, which may impregnate the fiber sheets to form composite laminates, which may be bonded to the ends of the core to form the composite sandwich. In some embodiments beyond the scope of the appended claims, the polymeric resin may include a mixture of one or more thermosets and a thermoplastic, such as epoxy or polyurethane with thermoplastic fibers mixed in (e.g., PEEK fibers). The polymeric resin may include one or more tougheners therein. The one or more tougheners may be compounded to cause curing of the one or more polyurethane or epoxy. In some embodiments, the polymeric resin may include a filler material. In some embodiments, the polymeric resin can include at least one Group VIII metallic material. In some embodiments beyond the scope of the appended claims, the polymeric resin can include a liquid mixture of a first thermoset, a second thermoset, and one or more additional materials, such as at least one hardener, at least one Group VIII metallic material, at least one filler, or at least one thermoplastic. In some embodiments beyond the scope of the appended claims, the polymeric resin can include a single thermoset, such as polyurethane or epoxy, and one or more additional materials, such as at least one second thermoset, at least one hardener, at least one Group VIII metallic material, at least one filler, or at least one thermoplastic. The polymeric resin can be sprayed onto the fiber sheet 510 using the pressure vessel 100 or 200 or a commercial spray system, or it can be manually applied to the fiber sheet 510 as described herein. The fiber sheet can be punctured to form holes that allow the polymer resin to flow and come into contact with the end of the core, which can be formed by plastic tubes.

The core may be a "soft" core or a "hard" core. The "soft" core may include cardboard, paperboard, low-density foam, and the like. The "hard" core may include a plurality of cells defined by plastic tubes, high-density foams, honeycomb, or the like.

The polymeric resin may also be used to form a composite laminate such as any of those described herein. U.S. Provisional Patent Application No. 62/007,652 (Attorney Docket No. P243722.US.01), entitled "Composite Laminate Free of Surface Defects," filed June 4, 2014, discloses details on apparatus and methods for manufacturing composite laminate free of surface defects, such as pinholes. Commercially acceptable vehicle body components may require that the surface be substantially free of pinholes, porosity, or other surface defects, such that the surface can exhibit a polished (e.g., glossy) surface finish.

The low-cost techniques described here have been developed to manufacture composite components free of surface defects.

FIG. 8 is a photograph of a composite sandwich including a "hard" core made of drinking straws in accordance with embodiments of the present disclosure. The composite sandwich 800 includes an upper composite laminate 802 or skin, a core formed by plastic straws 806 bundled together, and a lower composite laminate 804.

The upper composite laminate 802 and the lower composite laminate 804 include a polymeric matrix that embeds the randomly oriented discontinuous carbon fibers. The polymeric matrix includes a blend of epoxy and polyurethane foams, which is formed during the curing of a liquid blend of epoxy and polyurethane. The carbon fibers provide the reinforcement for the composite laminates 802 and 804. Those skilled in the art will appreciate that the polymeric resin can be used for any fiber-reinforced composite. The fibers can be carbon fibers, glass fibers, or plastic fibers such as polyamide (PA), polyethylene terephthalate (PET), polypropylene (PP), or polyethylene (PE).

In some embodiments, as explained in more detail below, the composite laminates may also include oriented or aligned continuous fibers embedded in a polymeric matrix. Oriented or aligned continuous fibers may have higher performance than staple fibers and may be more cosmetically appealing than staple fibers, such as woven fibers, but at a higher cost. The laminate that includes oriented continuous fibers may not stretch like the laminate that includes staple fibers. The staple fibers may be low cost recycled carbon fibers, for example, fibers recycled from RTM scrap fibers or other sources. The scrap fibers may cost less than unused virgin fibers.

Polymeric resin may have a gel time of about 40 seconds at about 130°C. Polymeric resin can cure at about 130°C in a few minutes. Cure time may vary depending on the epoxy supplier. For example, a Momentive EP05475 fast cure epoxy may cure more slowly than a DOW Chemical Voraforce 7500 epoxy. Specifically, the cure time may take about 5 minutes for Momentive's epoxy, while the cure time for DOW Chemical's epoxy may take about 3 minutes or less. When polymeric resin cures, the polyurethane may form microfoams through a reaction with water (e.g., condensation or small amounts of water contaminant) associated with the polyurethane or epoxy in the polymeric resin. In some embodiments, water or moisture in or adjacent to the polymeric resin may be converted to vapor by the heat of the curing process (e.g., at about 130° C.) which may cause a reaction with the polymeric resin, thereby forming a foam in the polymeric resin. The polymeric resin may shrink during curing. The shrinkage may be measured after curing. The polymeric resin may have a relatively low shrinkage after curing, such as equal to or less than 3% in any dimension. Low shrinkage is desired to help produce composite components with dimensional accuracy and consistency.

The carbon fibers may be dried prior to applying the polymeric resin because the polyurethane in the polymeric resin may chemically react with moisture in the fibers at an elevated temperature as explained above. In some embodiments, such a chemical reaction resulting in foaming may not be desirable.

Polymeric resin, which includes a mixture of a first thermoset (e.g., epoxy) and a second thermoset (e.g., polyurethane), optionally including a thermoplastic (e.g., blended thermoplastic fibers) to enhance the toughness (e.g., resilience) of the cured polymeric resin or filler material, can have several benefits over the thermoset alone. As discussed above, polymeric resin that includes a mixture of epoxy and polyurethane bonds well to plastic pipes and does not separate from them (e.g., flake off) like epoxy resin alone. Microfoams (e.g. polyurethane foams) formed from mixing and/or during curing adhere to the "hard" core (e.g. plastic pipes) very well so that the composite laminates do not peel off the "hard" core. For example, the microfoams so formed may extend at least partially into the interior of the cells or at least partially fill the cells (e.g. extend some distance towards the open ends of plastic pipes) to form a strong mechanical bond with the "hard" core. In contrast, a conventional epoxy in the composite laminate does not adhere to the "hard" core due to the lack of foam (e.g. microfoam) therein, but rather the composite laminates were found to easily peel off the ends of the "hard" core.

In addition, the polymeric resin may also be different from polyurethane such as VITROX used in Bayer Preg. For example, polyurethane microfoams may allow water to permeate through them and may be softer than epoxy. The polymeric resin that includes a blend of epoxy and polyurethane may provide a hard surface for the composite sandwich and may also be more water resistant than polyurethane alone. In some embodiments, a greater amount of epoxy may be used to impart an impermeable character to the surface of the cured composite part. In some embodiments, a layer or layers of epoxy or polymeric resins having a higher volume % of epoxy may be placed on one or more sides of the polymeric resin to impart an impermeable character to it.

Polymeric resin can transfer load between fibers. One thermoset may have better load transfer capability than another thermoset. For example, epoxy is harder than polyurethane and therefore has better load transfer capability to fibers than polyurethane, so a blend of two thermosets (e.g. epoxy and polyurethane blend), optionally a thermoplastic (e.g. blended thermoplastic fibers) may have improved mechanical performance. One thermoset may have higher resilience than another thermoset once cured. For example, polyurethane is tougher than epoxy (e.g. epoxies suffer brittle failure (crumble) at lower pressures than polyurethanes) and may allow a part that includes them to flex or bend rather than break.

Composite sandwich structures

The polymeric resins and fibers described above can be used to make composite structures such as a composite sandwich as described below. A composite laminate suitable for use in the composite structures of the present invention can be formed using one or more layers of fibers (e.g., fiber sheets) at least partially bonded in a polymeric resin. Any of the polymeric resins described herein can be used to form any of the composite laminate structures described herein, without limitation.

FIG. 9 illustrates a composite sandwich according to one embodiment of the invention. As shown, a composite sandwich 900 may include a core 906 sandwiched between composite laminates. Specifically, the composite sandwich 900 may include one or more composite laminates (e.g., one or more composite laminate layers), such as two composite laminates 908A-B on the bottom of the core 906, and an upper composite laminate 904. In some embodiments, the core 906 may include one or more "hard" components such as those formed from a plurality of cells defined by corresponding cell walls (e.g., plastic tubes such as straws or other equivalent structures). The core 906 may include a plurality (e.g., bundle) of at least similarly oriented tubular members (e.g., polycarbonate cells, such as straws), such as tubes 1 and 2. The tubes may be joined together, for example, by integral formation (e.g., extruded or molded together), an adhesive, thermal bonding (e.g., fusion) such as joining together after being individually extruded, or any other suitable joining means. The tubes may be composed to at least partially soften or melt upon application of a specific amount of heat. For example, the tubes may be composed to soften or melt and at least partially compress, while in a mold such that the resulting sandwich structure can at least partially conform to the shape of a mold. The length of each of the tubes prior to compression may be selected to provide a desired amount of elasticity upon application of heat and/or pressure thereto. For example, the length or height of the tubes may be about 100 µm to about 10 cm, about 1 mm to about 5 cm, about 5 mm to about 3 cm, about 250 µm to about 1 cm, about 1 cm to about 5 cm, about 1 mm to about 5 mm, about 5 mm to about 1 cm, about 7 mm, or about 1 cm. The tubes may have a substantially similar height and/or diameter. For example, the tubes may have a diameter of about 1 mm or more, such as about 1 mm to about 5 cm, about 3 mm to about 3 cm, about 5 mm to about 1 cm, about 6 mm, less than about 2 cm, or less than about 1 cm. While the cells (e.g., tubes) depicted herein have a circular cross-sectional shape, the cells may exhibit substantially polygonal cross-sectional shapes (e.g., triangular, rectangular, pentagonal, etc.), elliptical cross-sectional shapes, or amorphous shapes (e.g., with no set pattern or being a combination of circular and polygonal), when viewed along their longitudinal axis. The cells may be defined by a single integral structure with common walls between adjacent cells or tubes. While the term "cells" or "tubes" is used herein, in some embodiments the cells or tubes may include one or more closed ends; or exhibit configurations other than tubular (e.g., circular), such as polygonal (e.g., a plurality of closed or open pentagonal cells), or configurations having no sides connected to each other (e.g., baffles).

In some embodiments, the core 906 may include a "soft" component such as cardboard or paperboard. The cardboard or paperboard may provide sound dampening characteristics to the resulting sandwich structure. In some embodiments, the composite sandwich may include one or more layers of soft and/or hard components, such as in the core or having alternating cores of soft and hard components with one or more composite laminates between them. In some embodiments, the composite sandwich may include one or more core materials in one or more composite laminates (e.g., interposed between 908A and 908B). In some embodiments, the composite sandwich may include one or more core materials between composite laminates.

Composite laminates 904 and 908A-B may be formed from fibers 910, such as randomly oriented staple fibers (e.g., those shown in FIGS. 6 and 7) as shown, or continuous fibers, with cured polymeric resin therein. The fibers may include any fibers described herein, such as carbon fibers.

In some embodiments, the upper composite laminate 904 may be printed slightly (e.g., extended) toward one end of the core 906 in each of the cells (e.g., tubes) between the sidewalls 912, such as extending toward a point therein, as shown by dashed line 914A. The lower composite laminates 908A and 908B may also be printed slightly toward an opposite end of each tube (e.g., tubes 1-8) between the sidewalls 912, such as extending toward a point therein, as shown by dashed line 914B. Such printing may provide a mechanical bond between the core 906 and the composite laminate layer extending therein. The laminates may be printed to a greater extent adjacent to the center of each opening or cell of the tube, due to the distance from the sidewall supporting the composite laminate. The imprinting or protrusion of the composite laminates 908A or 908B may cause a corresponding indentation in adjacent outer layers of the composite material, which may extend to the surface of the composite material in the composite sandwich. This phenomenon is referred to as "direct imprinting." The direct imprinting may be deeper adjacent the center of the open end tube portion than near the side walls 912. The composite laminates 904 and 908A and 908B may have an imprint from the core 906 that results in a shallow depression or indentations in one or more portions of the composite sandwich 900, such as in the composite laminate 904, 908A, or 908B, and/or a non-crimped fabric layer. In some embodiments (not shown), the polymeric resin may extend substantially completely into the core 906 from one or both sides thereof.

The individual composite laminate layers may be about 0.2 mm thick or more when a polymeric resin embedding the fibers is cured. The resulting composite sandwiches, having one or more layers of laminates and/or composite cores, may be about 0.4 mm thick or more, such as about 0.4 mm thick to about 20 cm thick, about 0.6 mm thick to about 10 cm thick, about 2 mm thick to about 5 cm thick, about 5 mm thick to about 2 cm thick, about 1 mm thick, or about 5 mm thick.

The composite sandwich 900 may also include a non-crimped fabric ("NCF") reinforcement 902 or a woven fabric on top of the composite laminate 904. The NCF may be composed of two or more plies or layers of unidirectional continuous fibers or, in some cases, randomly oriented staple fibers, or a mixture thereof. Each individual layer may be oriented on a different axis or a different angle relative to another layer, for example, 0° and 90°, or 45° between any other angles. Depending on the number of layers and the orientations of each layer, a unidirectional, biaxial, triaxial, or greater configuration may be assembled into an NCF fabric system. The NCF or woven fabric may include a polymeric resin therein. The polymeric resin may be configured to provide a satisfactory surface finish to the composite sandwich 900. In one embodiment, the NCF 902 may have a biaxial configuration (e.g., fibers having a relative ratio of 0° and 90° to each other). The biaxial NCF has bi-directional strength and stiffness and flexible strength and stiffness. The NCF may provide higher pull-out loads or tensile strength in highly loaded areas than the composite laminates alone. The NCF 902 may also reduce printing from the composite core. The composite sandwich 900 may be used to produce automotive floors, among other applications. The composite sandwich 900 may also be used for an automotive body (e.g., finished surface) with the NCF 902 facing the exterior of the automotive body. The composite sandwich 900 may also include another NCF (not shown) in the lower composite laminates 908A-B to increase the toughness (e.g., pull-out load) of the composite sandwich.

FIG. 10 illustrates a composite sandwich according to one embodiment. As shown, the composite sandwich 1000 may include a lightweight core sandwiched between composite laminates. Specifically, the composite sandwich 1000 may include one or more composite laminates. For example, two composite laminates 1004A-B on the bottom of the core 906 and two upper composite laminates 1002A-B on top of the core 906. Each of the composite laminates 1002A-B and 1004A-B may be formed from fibers 910, such as a fiber sheet or a fiber mat that includes randomly oriented staple fibers (e.g., those shown in FIGS. 6 and 7) as shown, or continuous fibers, with cured polymeric resin. Composite laminates 1002A-B and 1004A-B may also be printed from core 906. Upper composite laminates 1002A and 1002 may be printed slightly toward one end of each tube (e.g., tubes 1-8) between sidewall 912, such as extending toward a point therein, as shown by dashed line 1014A. Similarly, lower composite laminates 1004A and 1004B may be printed slightly toward an opposite end of each tube, e.g., extending toward a point therein, as shown by dashed line 1014B. The laminates may be printed to a greater extent near the middle of each tube, due to the distance from sidewall(s) 912 supporting the composite laminate. In one embodiment, the composite sandwich 1000 may not include an NCF, such that it may have a lower pull-out load than the composite sandwich 900 that includes NCF. The composite sandwich 1000 may not have the same cosmetic appeal as the composite sandwich 900 due to the randomly oriented fibers in the composite laminates of the composite sandwich 1000, but may be used to manufacture components, including front and rear bulkheads for automobiles.

In some embodiments, the core 906 may be formed from a plurality of tubes (e.g., a unitary structure including a plurality of coextruded polycarbonate tubes that share common walls), similar to drinking straws. In some embodiments, the core 906 may be formed from a plurality of tubes (e.g., cells or tubular members) that are individually extruded and joined together thereafter. The core may have a density of about 70 kg/m3 and a cell height of about 7 mm. The core 906 may have a density of about 20 kg/m3 or more, such as about 20 kg/m3 to about 150 kg/m3, about 40 kg/m3 to about 100 kg/m3, about 60 kg/m3 to about 80 kg/m3, or about 65 kg/m3 to about 75 kg/m3. The core may have an initial cell height of about 100 µm to about 10 cm, about 1 mm to about 5 cm, about 5 mm to about 3 cm, about 250 µm to about 1 cm, about 1 cm to about 5 cm, about 1 mm to about 5 mm, about 5 mm to about 1 cm, about 7 mm, or about 1 cm. The use of polycarbonate, polyethylene, polypropylene, or other plastics in the core may provide greater tear resistance upon applying stress to the core than is found in paperboard or cardstock. For example, the core may include a plurality of integrally formed polycarbonate tubes (e.g., a plurality of open-ended structures joined together), which may collectively bend or otherwise distort in one or more regions upon application of stress, heat, and/or pressure in a mold, whereas paperboard may tear under the same conditions. In some embodiments, the core may be bent, compressed, or stretched in one or more regions thereof, depending on the geometry of the mold and the desired finished dimension of a part including it.

In some embodiments, the core may be fully compressed to form a solid substance or may be partially compressed to reduce the height of the core. The height of the compressed core may be about 15% or more of the initial core height, such as about 15% to about 90%, about 25% to about 75%, about 40% to about 60%, about 15% to about 50%, or about 15% of the initial core height. It will be appreciated that the number of composite laminates may vary at the top and bottom of the composite sandwich, such as having different layers or materials therein. The core dimension and density may vary, such as having more cells (e.g., tubes) in one or more regions thereof, having cells of larger or smaller diameter in one or more regions thereof than in adjacent regions, having one or more regions that include tubes having different (e.g., smaller or larger) wall thicknesses than tubes in adjacent regions, or combinations of any of the above. The weight of the fiber sheet or NCF may vary.

One or more of the carbon fiber reinforced (RCF) sheets or layers (e.g., 908A, 908B, 904, 1002A, 1002B, 1004A, 1004B) formed from randomly oriented staple fibers may have a mass or weight of about 150 g/m2 or more, such as about 150 g/m2 to about 500 g/m2, about 175 g/m2 to about 350 g/m2, about 200 g/m2, or about 300 g/m2. The carbon fibers in the RCF sheet may be recycled fibers or virgin fibers. The RCF may include waste fibers, such as from dry NCF waste, dry resin transfer molding (RTM) waste, or other leftover dry fibers. For example, Toray T700 60E carbon fiber can be cut from dry NCF waste to a 35 mm fiber and then formed into a randomly oriented fiber sheet with an areal density of approximately 200 g/m2. An additional NCF layer can have a mass or weight of approximately 300 g/m2 to further reinforce the composite.

FIG. 11 is a cross-sectional view of one embodiment of a component formed by a composite sandwich, a metal insert, and reinforced with an NCF. As shown, component 1100 may include a composite core 1106 between one or more upper composite laminates 1104 and one or more lower composite laminates 1108. Each of the composite laminates 1104 and 1108 may be formed from fibers, such as a fiber sheet or a fiber mat that includes randomly oriented staple fibers (e.g., those shown in FIGS. 6 and 7) as shown, or continuous fibers, with cured polymeric resin. Component 1100 may include a metal insert 1114 between core 1106 and one or more composite laminates, such as composite laminate 1108. Metal insert 1114 may include one or more surfaces extending parallel to the layers of the composite sandwich, such as non-tilt region 1118. Metal insert 1114 may include one or more surfaces extending non-parallel to the layers of the composite sandwich, such as tilted region(s) 1116. In some embodiments, the insert may be a non-metal such as a polymer or a ceramic. In some embodiments, one or more of the top or bottom composite laminates may include one or more layers of composite laminates and/or NCFs.

The composite core 1106 may be partially or completely compressed around the metal insert 1114 to at least partially conform to the shape of the metal insert 1114. The composite core 1106 may include one or more of an uncompressed portion 1106, a partially compressed transition portion 1106B, and a fully compressed (e.g., solid) portion 1106C surrounding the metal insert 1114. The partially compressed transition portion 1106B may be positioned between the fully compressed transition portion 1106C and the transition portion 1106B along the inclined region 1116 of the metal insert 1114. In some embodiments, the metal insert may include, but is not limited to, a lightweight metal, such as aluminum, titanium, magnesium, alloys including one or more thereof, or combinations of any of the foregoing. The fully compressed portion 1106C may be located above the untilted region 1118.

Component 1100 may also include an NCF 1102 above the upper composite laminates 1104. NCF 1102 may provide increased pullout load in a direction substantially parallel to the plane of the composite laminate (along the Y axis), substantially perpendicular to the cross section (X-Z plane) of component 1100 as shown in FIG. 11.

A composite sandwich that includes an NCF may provide sufficient strength to allow the composite sandwich, as shown in FIGS. 9 and 11, to be used for seat assemblies in automobiles. The seat assembly may require the composite to have a high pullout load. If the seat assembly is formed from a composite sandwich that includes an NCF on the top (e.g., outermost) of at least one of the composite laminates or on both the top composite laminates and bottom composite laminates, the NCF may help prevent the seat belt from pulling out of the seat assembly. For example, when an automobile suddenly stops, the seat belt may suddenly pull, thereby applying a tensile load on the seat assembly, which may pull through the composite laminate. By adding the NCF, the tensile load may be increased to provide more support so that the seat belt does not pull out of the composite laminates of the seat assembly.

FIG. 12 is a flow diagram of a method for forming a composite laminate structure according to embodiments of the present disclosure. The method 1200 may include mixing a polymeric resin in an action 1202. According to embodiments beyond the scope of the appended claims, the polymeric resin may include any polymeric resin disclosed herein. According to the invention, the polymeric resin may include a polyurethane and an epoxy, the epoxy having a greater load transfer capacity than the polyurethane. In one embodiment, the polymeric resin may include one or more of an epoxy, a polyurethane, a thermoplastic, a toughener, a filler, or a Group VIII metallic material according to any of the embodiments described herein.

Mixing the polymeric resin may include mixing the polymeric resin in situ prior to applying the polymeric resin. In embodiments beyond the scope of the appended claims, mixing the polymeric resin in situ may include mixing the polymeric resin by applying a first component (e.g., polyurethane) of a polymeric resin to a precursor component of a composite laminate structure such as a fiber sheet in a stack, applying at least a second component (e.g., one or more of an epoxy, hardener, filler, Group VIII metal, and/or thermoplastic) of the polymeric resin to the same or a different precursor component (e.g., a second fiber sheet in the stack) of the composite laminate structure, and causing the first component and at least one second component to come into contact with each other. In one embodiment, causing the first component and at least one second component to come into contact with each other may include pressing adjacent fiber sheets having the first component and at least one second component such that the first and at least one second components of the polymeric resin come into contact with each other. In an embodiment beyond the scope of the appended claims, applying a first component (e.g., polyurethane) of a polymeric resin and applying at least one second component (e.g., epoxy and/or thermoplastic) of the polymeric resin to the same or a different component of the composite laminate structure, and causing the first component and at least one second component to come into contact with each other may include applying the first component and at least one second component in direct contact with each other, such as in directly adjacent layers (e.g., contacting carbon fiber sheets). Such application may be by manual spreading or spraying. For example, the first component may be applied to the carbon fiber sheet on a side adjacent to the core blank and the second component may be applied to an opposite side of the fiber sheet.

Mixing the polymeric resin prior to application may include the methods described herein (e.g., mixing in a bag, a pressure vessel, a container, or a commercial spray system). The resulting structure may include a layered or pseudolayered polymeric resin mixture having a layer of the first polymeric resin component, a layer of at least one second polymeric resin component, and an intervening layer of a mixture of the first and at least one second polymeric resin components. For example, each layer may be about one-third the height of the polymeric resin-containing layers in the resulting cured part. In one embodiment, each individual polymeric component layer may be less than about 40% of the cross-sectional thickness of the portion(s) of the composite laminate structure that include the polymeric resins therein. In some embodiments, the first and at least one second component of the polymeric resin may be substantially completely mixed, such that the composite laminate structure made by such actions exhibits a substantially homogeneous cured polymeric resin therethrough. The method 1200 may include an action 1204 of heating and maintaining the polymeric resin at an application temperature. The application temperature may include a temperature set to provide a selected viscosity to the polymeric resin, such as a temperature selected to provide a viscosity to the polymeric resin suitable for low pressure spraying. In one embodiment, the application temperature may be between a room temperature and a curing temperature of a component (e.g., one or more of an epoxy, hardener, or polymer) of the polymeric resin. In the case of polymeric resins that include thermoplastics, the application temperature may be above the melting temperature of the thermoplastic. In some embodiments, the application temperature may be less than about 100°C, such as less than about 90°C, about 40°C to about 85°C, about 50°C to about 70°C, about 50°C, about 80°C, about 75°C to about 85°C, or about 65°C.

The method 1200 may include an action 1206 of applying the polymeric resin onto a fiber sheet (e.g., carbon fiber sheet) or the core. Applying the polymeric resin to the fiber sheet or the core may include spraying the polymeric resin at a pressure of less than 620528 Pa (6.2 bar, 90 psi) onto a fiber sheet and/or a mold. In one embodiment, spraying the polymeric resin at a pressure of less than 620528 Pa (6.2 bar, 90 psi) may include spraying the polymeric resin at a pressure of less than about 482633 Pa (4.8 bar, 70 psi).

In one embodiment, applying the polymeric resin may include manually spreading the polymeric resin onto one or more fiber sheets, the core, or any other component of a composite laminate structure. Manually applying the polymeric resin may include manually spreading the polymeric resin using a tool such as a trowel, brush, or spatula. In one embodiment, manually applying the polymeric resin may include manually spreading the polymeric resin by rolling the polymeric resin onto at least one fiber sheet or core with a roller carrying the polymeric resin thereon, such as a roller at least partially saturated with polymeric resin.

In one embodiment, applying (e.g., spraying) the polymeric resin may include applying more than one layer, or more than one polymeric resin onto a fiber sheet or multiple fiber sheets (e.g., separate fiber sheets). For example, applying a polymeric resin onto a fiber sheet may include applying a first polymeric resin onto a first carbon fiber sheet and applying a second polymeric resin onto a second carbon fiber sheet.

The method 1200 may include the action 1208 of placing the carbon fiber sheet into a plurality of cells, with the carbon fiber sheet extending across the open ends of the cells. The cells may be similar or identical to any cells (e.g., tubes) described herein, such as being at least partially defined by a plurality of polycarbonate tubes. Placing the carbon fiber sheet may include placing more than one carbon fiber sheet, such as two carbon fiber sheets on opposite sides of the core. In one embodiment, placing the carbon fiber sheet may include placing the carbon fiber sheet in a mold and placing a core adjacent thereto (e.g., above or below the carbon fiber sheet).

The method 1200 may include the action 1210 of curing the polymeric resin applied onto the carbon fiber sheet, for example, for less than about 10 minutes. In some embodiments, curing the polymeric resin may be performed after it is positioned according to action 1208. In one embodiment, curing the polymeric resin may include heating the polymeric resin, the composite laminate, or the composite sandwich, such as in a mold, or oven. Heating the polymeric resin may be performed at about 110° C. or more, such as about 120° C. to about 200° C., about 130° C. to about 180° C., about 140° C. to about 160° C., about 120° C., about 130° C., about 140° C., or about 160° C. In some embodiments, heating the polymeric resin may be performed for any suitable curing time described herein.

In some embodiments, the method 1200 may include placing the carbon fiber sheet into a core prior to curing; the core including any material or configuration for a core described herein, such as a plurality of closely packed polycarbonate tubes. In some embodiments, the method 1200 may include arranging one or more of the carbon fiber sheets, polymeric resin or components thereof, or core into a mold and applying pressure to at least partially close the mold to form a composite laminate structure having the shape of the mold and/or at least partially collapse the core. In one embodiment, heat may be simultaneously applied to at least partially heat one or more of the polymeric resin, carbon fiber sheets, or core. For example, the core may become more flexible upon application of heat during pressing, such that the core at least partially softens or melts, while being compressed to increase conformity to the shape of the mold. The polymeric resin may at least be started to cure by the application of heat in the mold.

FIG. 13 is a flow diagram of a method for forming a composite laminate structure in accordance with embodiments of the present disclosure. The method 1300 may include removing a stack (e.g., composite laminate precursor assembly) of a first fiber sheet, a core, and a second fiber sheet into a mold, in action 1302. For example, each fiber sheet may include one, two, or more individual fiber sheets bonded together. In one embodiment, disposing a first fiber sheet, a core, and a second fiber sheet into a mold may include impregnating one or more fiber sheets with a polymeric resin. In one embodiment, each of the first and second fiber sheets may be impregnated with a polymeric resin or component thereof by manually spraying and/or spreading the polymeric resin onto each fiber sheet before or after it is disposed into the mold. The polymeric resin may include any polymeric resin described herein. In one embodiment, different composite laminates (e.g., different layers of fiber sheets) may include the same or different polymeric resins than adjacent composite laminates. For example, in one embodiment, the composite laminates adjacent to the mold cavity may include a polymeric resin having a greater amount of epoxy (or only epoxy) therein to impart a water impermeability characteristic to the resulting composite sandwich. In one embodiment, one or more composite laminates may include a polymeric resin having a fire retardant (e.g., phenolic epoxy). In one embodiment, one or more composite laminates proximate the core may include a polymeric resin having a greater amount of polyurethane (or only polyurethane) therein to provide a desired amount of bonding between the polymeric resin and the core.

In one embodiment, the method 1300 may include applying a polymeric resin onto at least one carbon fiber sheet, for example, by spraying or manually spreading. In one embodiment, spraying the polymeric resin may be performed at a pressure of less than about 620528 Pa (6.2 bar, 90 psi) onto at least one fiber sheet. In one embodiment, applying (e.g., manually spraying or spreading) a polymeric resin onto at least one fiber sheet may include spraying a polymeric resin onto a first carbon fiber sheet and one or more additional carbon fiber sheets. In one embodiment, the method may include placing one or more carbon fiber sheets in the core, such as on the same side (e.g., a layered configuration) and/or on opposite sides thereof. For example, the method may include applying a polymeric resin onto a first carbon fiber sheet and a second carbon fiber sheet to at least partially impregnate the fiber sheets with the polymeric resin. The method may further include positioning the first carbon fiber sheet on a first side of the core adjacent to the open ends of the core and the second carbon fiber sheet on the second side of the core opposite the first side. Such positioning may be performed before or after the carbon fiber sheets have been at least partially impregnated with the polymeric resin. In one embodiment, the second carbon fiber sheet may be positioned on top of the first carbon fiber sheet. In one embodiment, the first carbon fiber sheet and/or the second carbon fiber sheet may include randomly oriented staple fibers, continuous fibers, or a carbon fiber NCF.

The method of preparing and applying (e.g., spraying) the resin may be similar or identical to the methods of preparing and spraying polymeric resins described above. The method of preparing and/or applying the polymeric resin (e.g., spraying) may significantly reduce the pressure required to flow the polymeric resin into the mold and impregnate the fibers, such as in resin transfer molding. In some embodiments, the core may be a "hard" core, for example, including a plurality of tubes joined together and having a first open end and a second open end, such as polycarbonate tubes. The mold cavity may be formed from a lower mold gate and an upper mold gate. In some embodiments, the core may be a "soft" core.

The method 1300 may also include disposing an NCF or woven fabric over one of the first fiber sheet and the second fiber sheet in the mold in action 1304. The NCF may strengthen the composite. The NCF may also reduce printing from the composite core. The NCF may further improve the quality of the laminated surface and enhance aesthetics.

Method 1300 may further include closing the mold at action 1306. Closing the mold may include applying external pressure to the mold, such as to compress one or more components therein. Method 1300 may also optionally include aspirating the mold cavity at action 1308. For example, it may be desirable to aspirate the mold to remove air entrapped in randomly oriented staple fibers when the composite laminate is formed from staple fibers. Conversely, continuous fibers may not entrap air as much as staple fibers, so it may not be necessary to aspirate the mold when the composite laminate is formed from continuous fibers. The method 1300 may also include curing the polymeric resin to form a composite component in action 1310. Curing the polymeric resin may include heating the fiber sheet having the polymeric resin in or on it (e.g., an at least partially formed composite laminate or a precursor thereof such as a stack) containing the polymeric resin in the mold or outside the mold to about 110° C. or more, such as about 120° C. to about 200° C., about 130° C. to about 180° C., about 140° C. to about 160° C., about 120° C., about 130° C., about 140° C., or about 160° C. Curing of the polymeric resin may take place for a duration of about 40 seconds or more, such as about 40 seconds to about 1 day, about 1 minute to about 12 hours, about 90 seconds to about 8 hours, about 2 minutes to about 4 hours, about 40 seconds to about 10 minutes, about 1 minute to about 8 minutes, about 90 seconds to about 5 minutes, about 3 minutes, about 6 minutes or less, or about 8 minutes or less. In one embodiment, heating/curing of the polymeric resin may be partially performed in the mold and then completed at a different location (e.g., oven). The resulting cured composite component may have any shape determined by the mold.

In some embodiments, a composite sandwich may include one or more cores, such as having more than one core separated by one or more composite laminate layers. For example, a composite sandwich may include a "hard" core of bonded circular plastic tubes and a composite laminate layer on either side thereof. The composite sandwich may include an additional "soft" core of cardboard adjacent to a composite laminate layer over the first "hard" core. The soft core may include at least one more composite laminate layer on the side opposite the hard core. In such embodiments, a desired toughness (e.g., resilience and/or hardness) and sound dampening may be achieved. In some embodiments, a composite sandwich may include one or more composite laminate layers having one or more fiber sheets that include one or more different or identical polymeric resins, respectively. For example, in one embodiment beyond the scope of the appended claims, a composite sandwich may include a core having a carbon fiber sheet thereon, the carbon fiber sheet may include a polyurethane polymer resin therein, and the carbon fiber sheet may be adjacent to another carbon fiber sheet having an epoxy therein. In such embodiments beyond the scope of the appended claims, the polyurethane may be applied to the stack in the mold separately from the epoxy in an adjacent layer. The resulting composite laminate structure may exhibit the desired energy absorption, break profiles, water resistance, and/or sound absorption.

In one embodiment, arranging a stack of a first fiber sheet, a core, and a second fiber sheet in a mold, and spraying the polymeric resin at a pressure of less than about 620528 Pa (6.2 bar, 90 psi) may include spraying a powdered filler material into a mold, placing a first fiber sheet thereon, spraying a first polymeric resin (e.g., an epoxy) onto the first carbon fiber sheet, placing a second carbon fiber sheet on the first carbon fiber sheet, spraying a second polymeric resin (e.g., polyurethane) onto the second carbon fiber sheet, and placing a core in contact with the second carbon fiber sheet. The stack may have the layered composition of a first polymeric resin on a first carbon fiber sheet, on a second polymeric resin on a second carbon fiber sheet, on a core. The same or a different configuration may be arranged on the opposite side of the core. The polymeric resins, carbon fiber sheets, and/or core may be similar or identical to any polymeric resin, carbon fiber sheet, or core described herein. In some embodiments, a filler material may be disposed on the mold prior to disposing any portion of the composite laminate therein. For example, a thin layer of filler material may be sprayed onto the mold prior to placing the carbon fiber sheets therein. The filler material may be incorporated into the polymeric resin subsequently sprayed thereon (on its surface) and serve to reduce shrinkage at least at the surface of the composite laminate formed therein without compromising the bulk mechanical properties of the composite laminate.

The composite sandwiches described herein may have good sound absorption, good thermal insulation, high bending rigidity, high energy absorption and light weight. The composite sandwiches may be used in various applications including automotive industry (e.g. chassis, automobile hood, body parts and the like), other vehicles (e.g. trucks), agricultural equipment, bicycles, satellite applications, aerospace applications, building materials (e.g. building materials and the like), consumer products (e.g. furniture, toilet seats and electronic products, among others).

Claims (29)

1. A method of forming a composite laminate structure (904, 908A-B), the method comprising: mixing a polymeric resin including a polyurethane and an epoxy, wherein the epoxy is less than 40% by volume of the polymeric resin and has a higher viscosity than the polyurethane; heating to and maintaining the polymeric resin at an application temperature between a room temperature and a curing temperature of one component of the polymeric resin, where the application temperature is between 40 °C and 85 °C, where the polymeric resin has a viscosity of 0.3 Pa s (300 centipoise) or less at the application temperature prior to application; apply the polymer resin on a fiber sheet; placing the fiber sheet over a core (906) that includes a plurality of cells (1-8) defined at least partially by corresponding cell walls (912), the fiber sheet extending through at least some of the plurality of cells; where the fiber sheet includes the polymeric resin applied thereon; and After placement, cure the polymer resin applied to the fiber sheet. 2. The method of claim 1, wherein heating and maintaining a polymeric resin at an application temperature includes: place the polymer resin in a container; placing the container in a pressure vessel containing a heated fluid, where the fluid is maintained at the application temperature. 3. The method of claim 1, wherein mixing the polymeric resin includes mixing a thermoplastic into the polymeric resin. 4. The method of claim 1, wherein mixing the polymeric resin includes mixing a curing agent or hardener into the polymeric resin. 5. The method of claim 1, wherein the hardener is configured to begin curing at 70 °C. 6. The method of claim 1, wherein the polyurethane and epoxy have the same cure time. 7. The method of claim 1, wherein mixing the polymeric resin includes mixing at least one Group VIII metallic material into the polymeric resin, the at least one Group VIII metallic material including one or more of cobalt, iron, nickel or ferrites. 8. The method of claim 7, wherein the polymeric resin includes less than 5% by volume of at least one Group VIII metallic material. 9. The method of claim 1, wherein the polymeric resin includes a filler material that includes one or more of calcium carbonate, silica or an alumina. 10. The method of claim 1, wherein: The polymer resin includes 10% to 35% by volume of the epoxy; and Mixing the polymeric resin further includes mixing one or more of a curing agent or hardener, a thermoplastic, at least one Group VIII metallic material, or a filler material into the polymeric resin prior to application. 11. The method of claim 1, wherein applying the polymeric resin includes spraying the polymeric resin at a pressure less than 620528 Pa (6.2 bar, 90 psi) onto the fiber sheet. 12. The method of claim 1, wherein applying the polymeric resin includes manually spreading the polymeric resin onto the fiber sheet. 13. The method of claim 1, wherein mixing the polymeric resin includes mixing the polymeric resin in situ in the mold. 14. The method of claim 13, wherein mixing the polymeric resin in situ in the mold, includes: apply the polymer resin polyurethane and apply the polymer resin epoxy to the fiber sheet; and cause the polyurethane and epoxy to come into contact with each other during the heating action and maintain the polymeric resin at the application temperature. 15. The method of claim 1 to 7, wherein the epoxy is 25% to 35% by volume of the polymeric resin. 16. A composite laminate structure (904, 908A-B), comprising: at least one core (906) including a plurality of cells (1-8) defined at least partially by corresponding cell walls (912) further defining substantially opposite open ends of each of the plurality of cells, the plurality of cells having a substantially parallel arrangement; one or more first composite laminates bonded to the first end of the core; and one or more second composite laminates bonded to the second end of the core; Each of the one or more first and one or more second composite laminates has a cured polymeric resin therein, the cured polymeric resin including a polyurethane and an epoxy, wherein the epoxy is less than 40% by volume of the polymeric resin; and a cured polymeric resin foam of the cured polymeric resin in one or more first composite laminates and one or more second composite laminates infiltrated at least partially into the open ends of the plurality of cells at the first and second ends of the core, the cured polymeric resin foam providing a bond between the first and second ends of the core and the first and second composite laminates. 17. The composite laminate structure of claim 16, wherein the polymeric resin in one or more of the composite laminates includes a filler material therein, the filler material including one or more of calcium carbonate, silica or an alumina. 18. The composite laminate structure of claim 16, wherein the one or more of one or more first or one or more second composite laminates comprises two or more composite laminates. 19. The composite laminate structure of claim 16, further comprising one or more paperboard or paperboard between the one or more first composite laminates and the one or more second composite laminates. 20. The composite laminate structure of claim 16, wherein one or more of the composite laminates include staple fibers or continuous fibers embedded in the cured polymeric resin. 21. The composite laminate structure of claim 20, wherein the staple fibers or continuous fibers include one or more carbon fibers, glass fibers or plastic fibers. 22. The composite laminate structure of claim 16, further comprising a non-crimped fabric or a woven fabric on one of one or more first composite laminates or one or more second composite laminates, the non-crimped fabric including the cured polymeric resin therein. 23. The composite laminate structure of claim 16, wherein the epoxy is 10% to 40% of the polymeric resin by volume. 24. The composite laminate structure of claim 22, wherein the epoxy is 25% to 35% of the polymeric resin by volume. 25. The composite laminate structure of any of claims 22 and 23, wherein the polymeric resin includes a hardener and the hardener is present in a ratio of about 1:100-1:3 by volume of the polymeric resin. 26. The composite laminate structure of any one of claims 23 to 25, wherein the polymeric resin includes a thermoplastic and the thermoplastic is 1% to 20% of the polymeric resin by volume. 27. The composite laminate structure of claim 25, wherein the thermoplastic includes one or more of polyetheretherketone, polycarbonate, polyether or polypropylene. 28. The composite laminate structure of any one of claims 22 to 27, the polymeric resin includes a filler material and the filler material is 1% to 30% of the polymeric resin by volume. 29. The composite laminate structure of any one of claims 22 to 28, wherein the polymeric resin includes a Group VIII metallic material and the Group VIII metallic material is 5% of the polymeric resin by volume or less.